Recovering a Corrupted Disk Label
Sometimes, a power or system failure causes a disk's label to become unrecognizable.
A corrupted disk label doesn't always mean that the slice information or the
disk's data must be re-created or restored.
The first step to recovering a corrupted disk label is to label
the disk with the correct geometry and disk type information. You can complete this
step through the normal disk labeling method, by using either automatic configuration or
manual disk type specification.
If the format utility recognizes the disk type, the next step is to
search for a backup label to label the disk. Labeling the disk with
the backup label labels the disk with the correct partitioning information, the disk
type, and disk geometry.
How to Recover a Corrupted Disk Label
- Boot the system to single-user mode.
If necessary, boot the system from a local CD-ROM or the network
in single-user mode to access the disk.
See Chapter 10, Booting a System (Tasks), in System Administration Guide: Basic Administration or Chapter 12, Booting a Solaris System With GRUB (Tasks), in System Administration Guide: Basic Administration for information on booting the system.
- Relabel the disk.
# format
The format utility attempts to automatically configure any unlabeled SCSI disk. If the
format utility is able to configure the unlabeled and corrupted disk, it will
display this message:
cwtxdy: configured with capacity of abcMB
The format utility then displays a numbered list of disks on the system.
- Type the number of the disk that you need to recover.
Specify disk (enter its number): 1
- Select one of the following to determine how to label the disk.
If the disk was configured successfully, follow Steps 5 and 6. Then go to step 12.
If the disk was not configured successfully, follow Steps 7–11. Then go to step 12.
- Search for the backup label.
format> verify
Warning: Could not read primary label.
Warning: Check the current partitioning and 'label' the disk or
use the 'backup' command.
Backup label contents:
Volume name = < >
ascii name = <SUN1.05 cyl 2036 alt 2 hd 14 sec 72>
pcyl = 2038
ncyl = 2036
acyl = 2
nhead = 14
nsect = 72
Part Tag Flag Cylinders Size Blocks
0 root wm 0 - 300 148.15MB (301/0/0) 303408
1 swap wu 301 - 524 110.25MB (224/0/0) 225792
2 backup wm 0 - 2035 1002.09MB (2036/0/0) 2052288
3 unassigned wm 0 0 (0/0/0) 0
4 unassigned wm 0 0 (0/0/0) 0
5 unassigned wm 0 0 (0/0/0) 0
6 usr wm 525 - 2035 743.70MB (1511/0/0) 1523088
7 unassigned wm 0 0 (0/0/0) 0
- If the format utility was able to find a backup label and the
backup label contents appear satisfactory, use the backup command to label the disk
with the backup label.
format> backup
Disk has a primary label, still continue? y
Searching for backup labels...found.
Restoring primary label
The disk label has been recovered. Go to Step 12.
- If the format utility was not able to automatically configure the disk, specify
the disk type by using the type command.
format> type
The Available Drives Type menu is displayed.
- Select 0 to automatically configure the disk. Or, select a disk type from
the list of possible disk types.
Specify disk type (enter its number)[12]: 12
- If the disk was successfully configured, reply with no when the format utility asks
if you want to label the disk.
Disk not labeled. Label it now? no
- Use the verify command to search for backup labels.
format> verify
Warning: Could not read primary label.
Warning: Check the current partitioning and 'label' the disk
or use the 'backup' command.
.
.
.
- If the format utility was able to find a backup label and the
backup label contents appear satisfactory, use the backup command to label the disk
with the backup label.
format> backup
Disk has a primary label, still continue? y
Searching for backup labels...found.
Restoring primary label
The disk label has been recovered.
- Exit the format utility.
format> q
- Verify the file systems on the recovered disk by using the fsck command.
For information on using the fsck command, see Chapter 22, Checking UFS File System Consistency (Tasks).
